Adjustable inductor for induction heating



Nov. 5, 1963 E. F. M BRIEN 09,

ADJUSTABLE INDUCTOR FOR INDUCTION HEATING Filed Jan. 27; 1960 FIG. I f

INVENTOR. EDWARD F. MO BRIEN ATTORNEY United States Patent 3,109,909 ADJUSTABLE INDUCTOR FOR INDUCTION HEATING Edward F. McBricn, Parana, Ohio, assignor to The Ohio Crankshaft Company, Cieveland, Ohio, a corporation of Ohio Filed Jan. 27, 1960, Ser. No. 4,927 Claims. ((il. 219-1039) This invention relates generally to the art of induction heating and more particularly to a heating inductor which is adjustable to selectively control its heating action on the particular workpiece being heated.

In the art of induction heating, frequently it is desired to heat several parts simultaneously in a single fixture. For example, it may be desired to heat simultaneously several valve seats of a cylinder head of an automotive internal combustion engine. An individual heat ing inductor is provided for each part which is to be heated, and in order to insure the proper heating of each part it is necessary to adjust each individual inductor to produce the desired heating efiect on the corresponding part. Heretofore, there has been no convenient and effective arrangement for this purpose.

The present invention is directed to a novel adjustable inductor arrangement which is particularly well suited for this purpose.

In accordance with the present invention, each inductor comprises a single-turn induction heating coil and a two-piece inductive core. One part of this core is fixedly secured to the heating coil, while the other part of the core is adjustab ly mounted for adjustment to project a predetermined extent axially beyond the heating coil so as to pi'oduce the desired heating effect on the part which is to be heated,

It is an object of this invention to provide a novel and improved adjustable heating inductor.

It is also an object of this invention to provide such an inductor having a core which may be readily and conveniently adjusted to produce the desired heating effect on the workpiece.

Another object of this invention is to provide such a heating inductor which may be incorporated in a fixture designed to heat several parts simultaneously.

Further objects and advantages of this invention will be apparent 'from the following detailed description of a presently-preferred embodiment thereof, which is illustrated in the accompanying drawing.

In the drawing:

FIGURE 1 is a top plan view, with parts broken away for clarity, showing a plurality of series-connected heating inductors for simultaneously heating a corresponding number of cylinder head valve seats;

FIGURE 2 is a vertical section through one of these inductors, taken along the line 2-2 in FIGURE 1; and

FIGURE 3 is an exploded perspective view showing one of these inductors.

Referring to the drawing, there is shown a cylinder head having a plurality of openings 11 which are to provide the valve seats in the cylinder head. The portions of the cylinder head at these several openings 11 constitute separate individual workpieces which are to be induction heated. It is to be understood that this is given merely by way of example as one typical application where a plurality of individual parts or workpieces are to be induction heated simultaneously in a single fixture.

The induction heating apparatus comprises a plurality of individual single-turn induction heating coils 12, 1-3, 14 and 15 which are connected in series with each other.

In one practical embodiment each of these induction heating coils is of rectangular hollow cross-section with'a central passage for circulating a suitable coolant liquid. The several single-turn induction heating coils are connected to each other through connectors 16, 1'7 and 18 of similar hollow rectangular cross-section. One end of the first heating coil '12 in the series is connected through such a connector 19 to one. side of a suitable A.C. power source. In like manner, one end of the final heating coil 15 in the series is connected through a similar connector 20 to the other side of this power supply. Suitable coolant lliquid is circulated continuously through the end connector 19, the first heating coil 12, the connector 16, the second heating coil 13, the connector 17, the third heating coil 14, the connector 18, the final heating coil 15 and the end connector 20. Several cooling passages may be provided for the heating coils, if desired.

In accordance with the present invention, there is provided at each induction heating coil a two-piece core arrangement, one part of which is fixed to the heating coil and the other part of which is adjustable axially oi the coil.

Referring to FIGURES 2 and 3, the fixed or stationary part of the core is an annular, generally cup-shaped member 21 having a circular recess 22 at one face which snugly receives the heating coil 12. As best seen in FIG- URE 2, the top wall 12a of the heating coil engages the downwardly-facing inner face of the core part 21 at the recess 22, while the outer side 12b of the heating coil engages the inner -face of a circumferential flange 23 on the core part 2h.

The stationary core pant 21 is formed with a rectangula-r opening 24 (FIGURE 3) through its flange 23 which snugly receives the fishtail leads 12c and 12d of the heating coil 12. These leads extend perpendicular to the coil proper to avoid coupling to the adjacent face of the valve head.

The stationary core part is for-med with a central, axial, screw-threaded opening 26- which is concentric with the axis of the heating coil 12.

In one practical embodiment, the stationary core part 211 is molded to the heating coil 12. However, it is to be understood that any other appropriate arrangement for fixedly securing the stationary core part 21 to the heating coil may be provided, if desired.

The adjustable part of the core is an externally-threaded rod or stem 27 which is dimensioned to be threadedly received in the screw-threaded opening 26 in the stationary core part 2-1. At its upper end in FIGURES 2 and 3, this stem or rod is cformed with a screw driver slot 28. The rod or stem 27 has a length substantially greater than the combined axial extents of the heating coil 12 and the stationary core part 21, so that the lower end of the stem 2'7 can project axially beyond the heating coil .12

and into the opening 11 in the cylinder head, as shownin FIGURE 2.

The lower or projecting end of the adjustable core part 27 may be of any suitable contour to match the profile of the work-piece being heated and it may have suitable recesses so as to enable changes in the heat pattern by lateral adjustment of the core part 27 with respect to the workpiece.

In the preferred embodiment, both the stationary core part 21 and the adjustable core part 27 are made of powdered iron.

An identical two-piece adjustable core is provided at each of the other heating coils 13, 1 4 and 15.

The axial position of the adjustable core part 27 determines the inductive heating effect of the heating coil on the corresponding portion of the cylinder block which is to be inductively heated. The axial position of this core par-t may be adjusted readily, simply by inserting the point of a screw driver or other tool into the slot 28 and turning the core part 27 a sumcient amount to move it to the desired axiatl position.

From the foregoing, it will be apparent that the illustrated embodiment of this invention provides a convenien-t arrangement for selectively adjusting the induction heating effect on each of a plurality of work parts. Such adjustment may be made at each of the heating coils to produce the desired heating effect when the coils are energized simultaneously.

It is to be understood, also, that the novel arrangement of the present invention may be advantageously employed where only a single workpiece is to be inductively heated in a fixture.

While there has been described in detail herein and illustrated in the accompanying drawing a specific presentiy-preferred embodiment of this invention, it is to be understood that various modifications, omissions and refinements which depart from the disclosed embodiment may be adopted without departing from the spirit and scope of this invention. For example, the threaded connection between the core parts might be replaced by a slip fit and set screw arrangement or by providing an interference fit between the core parts which would permit the adjustment of the axially projecting core part by tapping it with a weight. Also, if desired, the two-piece core may be arranged so that the inner part is stationary and the outer part is adjustable.

Having thus described my invention, I claim:

1. In combination with a single-turn induction heating coil having an opening and adapted to heat the sidewalls of an opening in a workpiece, a core comprising an inductive outer core member rigidly connected onto the heating coil and above said coil with an axial screwthreaded opening therein coxial with the opening in said coil, and an inductive inner core member threadedly mounted in said threaded opening and extending through said coil opening for adjustment axially of the heating coil to project a predetermined extent axially beyond the heating coil and into said workpiece opening.

2. In combination with a single-turn induction heating coil, a core comprising a generally cup-shaped member having a central axial recess therein which snugly receives the heating coil, said cupshaped member at one end extending radially across one end of the heating coil, said cup-shaped member having a peripheral flange which extends from said one end circumferentially of the heating coil, said cup-shaped member at said one end having a threaded central opening which is smaller than the inside diameter of the heating coil and is disposed coaxial with the heating coil, and an externally-threaded stem threadedly mounted in said threaded opening in the cup-shaped member and extending therefrom axially through the heating coil and beyond the opposite end of the heating coil.

3. In combination with an induction heating coil adapted to heat the sidewails of an opening in a workpiece, a core comprising a first core member rigidly connected onto said heating coil, a second core member supported by said first core member and means for adjusting said second core member with respect to said first core member to project said second core member a predetermined distance beyond said heating coil and into said opening.

4. The combination as defined in claim 3 wherein said first core member is generally cup-shaped and defines a recess which snugly receives said heating coil.

5. The combination as defined in claim 3 wherein said adjusting means comprises, said first core member being above said coil, a threaded aperture in said first core member, said aperture being smaller than the inner diameter of said coil, a threaded external portion on said second core member, said threaded external portion being smaller than the inner diameter of said coil and adapted to be extended through said coil and threadably adjusted in said threaded aperture.

References Cited in the file of this patent UNITED STATES PATENTS Emerson Mar. 25, 

3. IN COMBINATION WITH AN INDUCTION HEATING COIL ADAPTED TO HEAT THE SIDEWALLS OF AN OPENING IN A WORKPIECE, A CORE COMPRISING A FIRST CORE MEMBER RIGIDLY CONNECTED ONTO SAID HEATING COIL, A SECOND CORE MEMBER SUPPORTED BY SAID FIRST CORE MEMBER AND MEANS FOR ADJUSTING SAID SECOND CORE MEMBER WITH RESPECT TO SAID FIRST CORE MEMBER TO PROJECT SAID SECOND CORE MEMBER A PREDETERMINED DISTANCE BEYOND SAID HEATING COIL AND INTO SAID OPENING. 